Bathroom remodel > Horizontal wet venting questions with drawings

i'm about to remodel my master bathroom and will be re-doing plumbing. The layout will be the following:
Shower, sink, WC and bathtub.

Here are drawings of what i was thinking of for the rough-in:

*** btw, i know the wye fittings for shower and lavatory are 3x3x3in while they should not. I could not find/draw.

The 3 inches drain cannot be moved and sits below a window. For that reason, there's a 3inches horizontal wet vent that goes left until it meets a thick wall then straight up through the roof. This is the actual drainage setup except we don't have a separate shower and fixtures are moved around a little.

So the plan is:
Shower: horizontal connection to 3 in wet vent through Wye, vented by the 3 in vent.
Sink: horizontal connection to 3 in wet vent through Wye, vented with the use of an AAV. The reason is that there's an exterior wall behind and i live in a cold climate where it can drop to -30 in winter. I think a vent in an exterior wall is not a good idea.
WC: horizontal connection to 3 in wet vent through Wye.
All of the above connected to 3 in drain through a double sanitary tee. The shower is about 7 feet from the 3in stack.

The bathub is on the other side of the 3in stack and would be connected in the 3in sanitary tee with a 1 1/2 to 3in adaptor. It would have a proper vent going 45degrees up until it reaches a wall then up in the attic. The vent would then go horizontal until it meets the 3in vent going through the roof.

I would like to know if this design make sense, what could i do to improve or am i completly wrong?

More specific questions:
1. is the 3in vent going straight up is too far (8 feet) from the stack to act as part of a wet vent?
2. Can i connect the WC the way it is in the drawing?
3. Is the double sanitary tee the proper fitting to allow the wet vented section AND the bathub to drain in the 3in stack? Can i cap the double sanitary tee as there is no pipe going up?
3. is it ok if i use an AAV for the lavatory or i should make some kind of plumbing loop like this:

OK, it's hard to make out but..... the lav will need it's own vent because if you drop to the floor like that you will have an S trap. Remember, anytime waste goes down, vent goes up. The shower may or may not be too far from the stack depending on your code but IPC says 6' for 2" and the UPC says 5' IIRC. The double san tee is Ok and is really OK if you use the top of it for a clean out otherwise I would rather see a double elbow there. Provided the vent next to the tub runs as you have drawn it, it will serve the tub and toilet but it's way too far from the shower.

OK, it's hard to make out but..... the lav will need it's own vent because if you drop to the floor like that you will have an S trap. Remember, anytime waste goes down, vent goes up. The shower may or may not be too far from the stack depending on your code but IPC says 6' for 2" and the UPC says 5' IIRC. The double san tee is Ok and is really OK if you use the top of it for a clean out otherwise I would rather see a double elbow there. Provided the vent next to the tub runs as you have drawn it, it will serve the tub and toilet but it's way too far from the shower.

Click to expand...

OK for the lav, will figure out a way to vent.
I measured the distance from the shower wye to the stack and it is exacly 6 foot so i guess i'm "OK".

For the remaining question, are the fittings i used to drain the toilet ok? 90 elbow to a wye then the sanitary tee... one after the other.

I don't know about aav in Canada. I can't believe any inspector would allow the island vent at the lav. Such techniques are reserved for situations where no proper vent is possible. Being hard to do or inconvenient does NOT qualify as "not possible".

Having proper cleanouts installed is one thing. Access through the floor to drain pipe does not make any sense. Water and drain installations should be considered "life-of-the-house" and planning for access probably causes more problems than it would solve.

That sanitary cross would not be acceptable in most jurisdictions, and a cleanout at the second floor level is usually cosmetic, but not practical. The vent for the shower is the one going up the wall, so unless the shower is over 5' wide it is acceptable, although, some areas would have a problem with it being a horizontal vent.

Ok, i guess i'll forget that idea. It really is my first big reno project and the plumbing part scares me a little. I want to DIY for the satisfaction of it. The answers i got on the post are very helpful.

Hi everybody and thanks for the help (that i got 9 months ago). I though i'd drop by and post a few pics of that bathroom remodel project i started and completed in april 2012. It's not perfect but given i'm a computer guy... i'm happy with the outcome.

The beast

First plumbing project ever.... used lot of copper.

How the the WC draining end up.

Worst part of the project.. tiling.

I'd post more pictures but can't go over 5.

Without the help of such forums i'd never been able to pull that DIY project.